Why is grounding important in electrical systems?
The electricians know very well: if a motor or a device fails in a plant, other motors and devices begin to fail repeatedly, but if the measurement does not reveal any abnormal condition in the voltage, the cause of the malfunctions may be the only cause, and that there is a ground fault in the system. Events like this are generally encountered in facilities that are getting old.
In fact, if there is a voltage difference in such faults, if a voltage value between ground and phase is measured, it is possible to see a voltage value above the phase-to-phase voltage. In this case, when the defective devices are checked, it is seen that there is a contact between the metal parts of these devices and the parts under tension and a small arc occurs.
By system grounding, it is meant that the operational grounding is not made or is problematic. If the operation is not correctly grounded, transient overvoltages occur in any phase and ground fault in the system. This may also cause some voltage increase in plants with poorly grounded ground. This is why the motors or devices in operation fail repeatedly. Therefore, it is possible to prevent over-voltages in the system by earth and phase failure on the one hand, and to prevent malfunctions of the devices in the system on the other hand, only by ensuring that the operational grounding is performed correctly. Only in this way can the reliability of the plant be ensured.
Thanks to a properly designed and applied earthing system, both the life safety of the people and the devices and equipments in the system will be protected against failures in the electrical installation. Otherwise, if a good grounding is not done, the reliability of the system will decrease and the devices will be damaged and even the life safety of the people will be compromised.
The objective of establishing a good grounding system in an enterprise is generally:
- Ensuring the safety of employees
- Protect electronic devices against the harmful effects of voltage surges
- Protect computer systems and sensitive electronic devices against the harmful effects of radio frequencies
Grounding is a vital precaution in the event of an electrical leakage of electrical powered machines and equipment. With grounding, in the simplest sense, the leakage electricity is given to the ground with the help of a conductor. It is absolutely necessary to ground the leakage electricity both in terms of not a life-threatening and in terms of the service life of the machinery and equipment. In this way, the excess electrical charge in the device is transferred to the earth with a lower resistance.
Generally, the buildings are supplied with electricity, phase and neutral lines. For all electrically driven equipment, these two lines are required. However, a third line, grounding, is needed to ensure the safety of these equipment.
Depending on the purpose of the application is made three different grounding:
- Protection grounding is done to ensure the safety of people and property in case of danger. In addition to the electrical parts of the electronic devices, the earthing of the outer metal surfaces which do not have current but which may cause the danger of conducting electricity to people in case of an electrical leakage is carried out for this purpose. For example, protection grounding is made for escalators.
- Operation grounding is done in order to ensure that the electrical current value is the expected value.
- Function earthing is only performed for a specific purpose. For example, grounding of rail systems or protection against lightning.
Grounding Inspection What are the basics?
Grounding is a very important issue and grounding has been made compulsory by various legal regulations. Certain major legal acts issued are:
- Earthing Regulations in Electrical Installations: This regulation covers the principles for the establishment, operation, supervision, and security of life and property safety in alternating current and direct current electrical installations with frequency less than 100 Hz.
- Electrical Power Plants Regulation: This regulation covers the principles for the establishment, operation and maintenance of electrical power plants in terms of safety of people and property.
- Electrical Indoor Facilities Regulation: This regulation covers the principles for the establishment, operation and maintenance of electrical indoor facilities in terms of safety of people's lives and property.
Apart from these, there are other legal regulations. These legal regulations include periods for the inspection, measurement and control of various grounding facilities. For example,
- In industrial plants and trade centers, inspection and measurements of resistances for earthing must be performed at least once a year and other inspections, measurements and controls related to earthing facilities should be carried out every two years.
- In addition to energy transmission and distribution lines, electricity generation, transmission and distribution facilities controls should be performed every two years.
- The control of the energy transmission and distribution lines should be carried out every five years.
- In non-stationary installations, fixed operating elements must be checked at least once a year, and for relocating operating elements, 6 must be carried out once a month.
- Grounding facilities must be inspected at least once a year in the facilities covered by the Regulation on Precautions to be Taken in the Workplace and Measures to be Taken with Flammable, Explosive, Dangerous and Hazardous Substances.
The following standard shall be taken into consideration during the controls to be carried out by the Ministry of Labor and Social Security in accordance with the provisions of the Regulation on Health and Safety Conditions in the Use of Work Equipment in 2013:
- Electrical equipment - Used in explosive atmospheres - Part 60079: Design, selection and installation of electrical installations
In the annex of Maintenance, Repair and Periodic Inspections (Annex 3) of this regulation, the grounding checks under the heading of Installations should be carried out by electrical engineers, electrical technicians or high technicians.
